Our lab studies the role of sensory input on the formation and refinement of neural circuits within the olfactory system. Our current focus is on understanding the basis of a robust form of cellular plasticity exhibited by a class of neurons in the olfactory bulb called external tufted cells which give rise to an intrabulbar map and ask how this plasticity is modulated by olfactory stimuli. [unreadable] [unreadable] We have previously described the dramatic anatomical basis of this plasticity which has no critical period (Marks et al., 2006), and are now extending these studies to explore the functional and molecular aspects of this plasticity as well. Making progress in these two areas is central to our goals. At an anatomical level we have already carried out an extensive study to determine that loss of odorant induced activity disrupts the development organization and maintenance. More recently, we have been investigating the affect that re-introduction of normal odorant induced activity can have on restoration of the intrabulbar of this map. Similarly we are pursuing electrophysiological studies to determine the functional role of intrabulbar projections as well. Finally, at a molecular level we have also developed an in-vitro slice assay that allows us to test the function of candidate proteins that may be involved in regulating intrabulbar map formation and plasticity.